A University of Rhode Island professor is coming under fire for taking to Twitter to call the National Rifle Association (NRA) a terrorist group and for calling for NRA CEO Wayne LaPierre to be held accountable following the murder of 26 people in Newtown, CT last Friday.

Erick Loomis, a history professor, went on a rant that included blaming the NRA for the murders and calling its members terrorists. Loomis has come under fire in recent days for saying he wants LaPierre’s “head on a stick,” which led conservatives to claim he was calling for the NRA’s chief assassination.

Loomis has since deactivated his Twitter account, but he took to his blog to explain what he meant with his rant.

“So to clarify, I want to make it blindingly clear that I did not call for the assassination of Wayne LaPierre,” he wrote Tuesday. “In my world, calling for someone’s head on a stick is a metaphor to hold them responsible for their actions. I think the last time “head on a stick” actually meant murder was sometime around 1450. That anyone would take this seriously as a murder threat is completely absurd. What stinks about it is that it has now involved my family, colleagues, and university. So I’ll apologize to them and to anyone legitimately offended by my metaphor.”